eagle facts

During the twentieth century, bald eagle populations struggled for
survival. Hawks and eagles were shot for sport because it was believed that they ate livestock.
In 1940, the National Emblem Law was passed, which forbade the killing of bald eagles in the lower
48 states. Alaska continued to encourage the killing of eagles and until 1962 there was a bounty
on them - $2 for each set of talons brought in.

This aggressive hunting had greatly reduced the population. The use of DDT brought the bald
eagle to the edge of extinction. DDT and other pesticides weakened the shells and the eggs were not able to
survive. The population did not recover until DDT was banned and scientist made an effort to
manage populations

Eagles cannot reproduce until they reach they are 5 years old. This also had an impact on
dwindling populations.

Bald eagles are large birds with a wing-span of 7 to 8 feet. One way to identify them in flight is that they hold
their wings out straight, like a plank, while soaring.

The female is larger than the male. It is difficult to determine relative size when seeing
birds from a distance. Usually the size difference can only be noted when the birds are sitting together.

It takes 4 or 5 years for eagles to gain the plumage that we associate with
a bald eagle, the white head and tail.

During the first two years, the birds are mostly dark brown with a mottling of white on their
tail and under their wings.

In the third year, the head becomes whiter but the tail remains mottled brown and white.

During the fourth year, the head and tail become a bright white and the body is all dark.

Bald eagles mate for life. If an eagle loses its mate, the mate is replaced. Mated pairs can be seen
sitting close to each other near the nest site. One bird sometimes preens the other. Copulation usually
occurs on or near the nest. Stages in the breeding cycle:

Nest-building This starts in December or January in New Jersey. The mated pair use the
same territory every year. If they have left the territory for better feeding grounds, they usually return at this time. The same nest may be
used year after year or a new one may be built. Some eagles have a number of nest sites and switch from year to
year. Even if an old nest is re-used, the eagles build it up, with branches collected from the ground. They may
add a foot or two of material to an old nest.

Egg-laying and Incubation Bald eagles usually lay one to three eggs. They are laid two to four
days apart. Incubation last 34 to 36 days. Both eagles incubate the eggs. The eagles hunker
down on the nest, so it can be difficult to see them. While one eagle sits on the nest, the other
hunts for food or perched nearby to protect the nest.

Nestling Phase The eggs hatch several days apart. For the first two weeks, the parents brood the
young often, sitting on the chicks to protect them and keep them warm. The eagles watch their young
continuously, either sitting on the nest or perched nearby. They feed the young four to eight times a day.
The parents tear off bits of prey and feed them directly, bill to bill. Chicks continue on the nest
for 10 to 12 weeks. By the time chicks are 9 weeks old, they are fully grown.

Fledgling Phase Once an eagle has taken a flight, it enters the fledgling phase of development. For the
first 6 weeks, it will stay close to the nest site and the parents. They may still return to the nest. They start to
follow their parents on hunting trips during this time. Then the fledglings begin to wander further from their nest area.
Seven to eight weeks after fledging, they may start to move further distances. If the eagles of
the area migrate, they may begin to migrate. If the eagles do not migrate, they may just move to an area
that has more food.

Juveniles Juvenile eagles travel for the first four years of their lives.
They travel in search of food, wandering across North America. During the first year of life, the
eagle mortality rate is more than 50%. But once they have mastered the survival skills they require, their
survival rate is much higher. At around 4 years, an eagle will find a mate and establish a territory. Their first year
together, they may build a nest, but might not reproduce.

With fish as the primary source of food for New Jersey eagles, the habitat that they prefer
are forests located near bodies of water. This is their favored foraging habitat. Eagles like
to perch in tall trees when fishing. In the winter, open bodies of water are necessary. In New Jersey,
the Delaware bay shore, with its tidal areas, usually has open water. Some parts of the Delaware
River remains open as well as some deep reservoirs.

Eagles do not migrate in the way that many other birds do, but they will move from one area to
another in search of food, particularly in winter. In New Jersey, most of the mature eagles that have
established nests tend to stay in the area of their nests.